Production of liquid polymers from



Patented Feb. 27, 1951 2,543,685 ICE PRODUCTION OF LIQIF'ID POLYMERS FROM DIHYDROPYRAN John George Mackay Bremner, Norton-on-Tees,

England, assignor to Imperial Chemical Industries Limited, a. corporation of Great. Britain No Drawing.

Application February 13, 1947, Se-

rial No. 728,385. In Great Britain February 26,

8 Claims. I This invention relates to the production of valuable organic liquids.

There has been disclosed in British Specification No. 573,507 a method for the production of than those mentioned. Working at atmospheric pressure space velocities of up to l hour that is 1 liter of liquid dihydropyran per liter of catalyst volume per hour, are suitable, and space veacrolein and ethylene which comprises heating 5 locitiesinthe neighborhood of 0.4 hour are pre- 2,3-dihydropyran at a temperature exceeding ferred. In general with increasing temperature 350 0., and in particular at temperatures withmore viscous products are obtained. in the range 450-500 C. The reaction may be conducted, for example, in

We have now found that by heating 2,3-dia tubular reactor constructed of arefractory mahydropyran in the presence of a dehydration l0 terial inert to the reactants and/or products, for catalyst within a certain temperature range example, heat-resistant glass, such as borosilhereinafter defined, there are produced polyicate glass. This tube is packed with the catameric compounds, in particular mobile, relatively lyst which is preferably granular. The catalyst high boiling liquids. may be arranged as a continuous bed, or on the According to the present invention, therefore, spaced bed principle, that is with layers of catathere is provided a process for the production of lyst separated from one another by a non-catapolymeric substances. in particular mobile, relalytic refractory material. Careful temperature tiveiy high boiling liquids, which comprises subcontrol is desirable. jecting 2,3-dihydropyran to temperatures of The dihydropyran may be produced in situ, 150350 C. in the presence of a dehydration for example by subjecting tetrahydrofurfuryl alcatalyst. The reaction may be conducted in the cohol in the vapor phase to a temperature of liquid or vapor phase, but is of particular value about 350 C. in the presence of a dehydration in relation to the vapor phase. Superatmoscatalyst, and then subjecting the products to the pheric pressure may be employed if desired. process of. the present invention. Thus, for ex- While any dehydration catalyst may be emample, a mass of a dehydration catalyst such as ployed it has been found that acidic catalystsv basic aluminium phosphate may be arranged to such as aluminium silicate; acid extracted kaohave a temperature gradient through it such that lin; artificial and naturally occurring zeolites the tetrahydrofurfuryl alcohol comes in contact such as acid extracted bentonite and Terrana with catalyst maintained at about 350 C. and earth; phosphoric acid on kieselguhr; alumina on then passes to a region containing dehydration silica gel, are very suitable. Preferably all these catalyst maintained at 150-350 C. When the catalysts are employed in granular form, e. g. reaction is conducted in the liquid phase, it is, as pellets. of course, necessary to employ superatmospheric While these valuable polymers may be obpressure. I tained by operating within the aforesaid range The products of the present invention are of temperature improved yields can be obtained chiefly highly mobile, high boiling liquids but a by suitable selection of space velocity andpressmall proportion of resin-like solid polymers sur h the use Of h h Space velocities and/ suitable, for example, as resin modifiers is also or the use of inert diluent or carrier gases, perobtained. The liquid polymeric substances are mits the use of higher temperatures within the suitable for use as hydraulic fluids in mechaniaforesaid range. With acidic catalysts it has cal systems and as solvents. They are also suitbeen found most suitable to operate at atmosable for use as modifiers of synthetic resins and pheric pressure within the range 250-350 C., other polymers. and preferably Within the range 300-350 C. The characteristics of representative polymers When superatmospheric pressure is employed and the reaction conditions employed in their the preferred ranges of temperature are lower production are given in the following table.

Table Reaction Conditions Properties of polymers Viscosity, Composition by Temp., Space centiweight; per cent Pressure 0. velocity, Catalyst B. P., C. r1 poises hours- @20 C.

{rt-crease; as a; a: a; a Do w mama: as is as 2;; 1s

3 The invention is illustrated but not limited by the following examples.

Example 1 A vertical silica tube, one inch in diameter, was packed with pellets of an aluminium silicate catalyst, the catalyst volume being 200 mls., and maintained at 300320 C. A stream of nitrogen, as carrier, was passed in at the top of the tube at a rate of 4 liters per hour together with 2,3- dihydropyran at a rate such that 262 mls. were fed in 6% hours, and there was collected from the bottom of the tube 185 mls. of a brown, oily liquid and mls. of a lower aqueous layer. The oily liquid was distilled to give 114 mls. of a liquid boiling at 62105 C., which was chiefly impure 2,3-dihydropyran, and 23 mls. of a fraction boiling at 105180 C. The residue, comprising 43 mls., was a very mobile liquid having a molecular weight of 200 as compared with 84 for dihydropyran. Analysis of this liquid showed that some dehydration and polymerisation had occurred. On distillation at reduced pressure there was obtained in good yield a stable, strawcolored, mobile liquid having a B. P. of '70-130 C./23 mms. of mercury and which was immiscible with water.

The aluminium silicate catalyst was prepared as follows. 228 gms. of flake caustic soda was dissolved in 8 gms. of a commercial sodium silicate containing 9% NazO and SiOz to give the composition NazSiOz and the product was dissolved in 60 mls. of distilled water and heated to 70 C. This solution was then pumped during about hour via a spray nozzle to a solution of aluminium nitrate prepared by dissolving 30 gms. of A1(NO3)39H2O in 60 mls. of water also heated to 70 C., the mixture being agitated the while. The precipitation was completed by the addition of 12.8 mls. of aqueous ammonia and after the addition of 80 mls. of water the mixture was allowed to stand for 18 hours. The precipitate was filtered oif and well washed, and was dried at 105 C. and ignited at 500 C. It was then pelleted with the aid of a small amount of graphite.

ExampZe 2 250 gms. of 2,3-dihydropyran was passed over a catalyst comprising phosphoric acid supported on kieselguhr (catalyst volume, 200 mls.) maintained at about 275 C. at a liquid space velocity of 0.4 houremploying 0.1 hour of nitrogen as carrier gas. There were obtained as product 69 gms. of organic liquid and 29 gms. of separable water.

The liquid on distillation at atmospheric pressure yielded 30 gms. of a fraction with a boiling range of 86200 C. (principally 1'71200 C.) and 6 gms. of a fraction boiling at 200-2'70 C.

The pass conversion of 2,3-dihydropyran was 94%.

Example 3 350 gms. of 2,3-dihydropyran was passed over aluminium silicate granules (volume 200 mls.) maintained at a temperature of about 277 C. at a liquid space velocity of 0.55 hour employing' 0.15 hourof nitrogen as carrier gas. There were obtained as product 234 gms. of organic liquid and 15 gms. of separable Water.

The organic liquid was distilled at atmospheric pressure and yielded 25 gms. of a fraction boiling at 86172 C. and a residue amounting to 90 gms. On distillation of this residue at a pressure of 1 mm. of mercury there were obtained: 16 gms. of a fraction boiling at 4080 C./1 mm.; 12 gms. of a fraction boiling at 150 C./1 mm.; 17 gms. of a fraction boiling at 150-226 C./1 mm.; 5 gms. of a fraction boiling at 220-250 C.; and a residue (27 gms.) comprising a black brittle resin. This resin had a softening point of -90 C. and was easily soluble in benzene, carbon tetrachloride furfural and other solvents.

The pass conversion of 2,3-dihydropyran was 66%.

I claim:

1. Process for the production of polymeric substances which comprises subjecting 2,3-dihydropyran to temperatures of -350 C. in the vapor phase under super-atmospheric pressure in thepresence of an acidic dehydration catalyst.

2. Process for the production of polymeric substances which comprises subjecting 2,3-dihydropyran to temperatures of 150-350 C. in the vapor phase in the presence of an acidic dehydration catalyst.

3. Process for the production of polymeric substances which comprises subjecting 2,3dihydropyran to temperatures of 150-350 C. in the vapor phase in the presence of aluminium silicate as catalyst.

4. Process for the production of polymeric substances which comprises subjecting 2,3-dihydropyran to temperatures of 150-350 C. in the vapor phase at atmospheric pressure in the presence of an acidic dehydration catalyst.

5. Process as claimed in claim 4 wherein ,a temperature of 250350 C. is employed.

6. Process for the production of polymeric substances which comprises subjecting 2,3-dihydropyran to temperatures of 250350 C. in the vapor phase at atmospheric pressure in the REFERENCES CITED The following references are of record in the file of. this patent:

FOREIGN PATENTS Number Country Date 877,313 France Sept. 1, 1942 558,106 Great Britain Dec. 21, 1943 

8. A LIQUID DIHYDROPYRAN POLYMER OBTAINED BY SUBJECTING 2,3-DIHYDROPYRAN TO TEMPERATURES OF 150* TO 350* C. IN THE VAPOR PHASE IN THE PRESENCE OF AN ACIDIC DEHYDRATION CATALYST. 